Method for recycling coolant for a cutting machine

ABSTRACT

In a metalworking process, an aqueous based degreasing solution which is used to clean manufactured parts, is recycled as a component of an aqueous based coolant fluid which is employed in the metalworking process used to fabricate the parts.

This is a continuation of application Ser. No. 08/243,574 filed on May16, 1994, and now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a method and apparatus ofrecycling and reusing an aqueous degreasing solution for further use asa component of a coolant solution which is itself recycled and reused inmetal cutting machines.

2. Description of the Prior Art

The metal working industry is one of the most heavily regulatedindustries. One area of this industry that is being scrutinized is thedegreasing operation. That is, the metal parts coming out of the cuttingmachines are covered in metal working fluids and residual lubricants.This occurs because oils are used as lubricants as the raw materialmetal is cut to form the finished part. Traditionally, heavy,non-soluble oils were used as lubricants. Vapor phase degreasing was themethod of choice for the removal of non-soluble oils from the finishedparts. Popular vapor phase degreasers are halogenated solvents such asFreon 113; 1, 1, 1-trichloroethane, trichloroethene, methylene chloride,and tetrachlorethene. These first two are suspected ozone depleters, andthe remaining three are suspected carcinogens.

With the introduction of lighter, soluble oils as lubricants in themetal cutting industry, the use of aqueous phase degreasers became apossibility. However, because of the fear of corrosion and also theexpense of converting from a vapor to an aqueous phase degreasingprocess, vapor phase degreasing remained the method of choice.

With the advent of new and more stringent environmental regulations,vapor phase degreasing is becoming a disfavored method of cleaning metalparts. This is so because two of the more common vapor phase degreasersare Freon 113 and 1, 1, 1-trichloroethane, substances suspected todeplete the earth's ozone layer. In 1990, Congress passed more stringentlaws providing that all parts manufactured by a process involving anozone depleting substance must be labeled to that effect. This hascaused many companies to look to aqueous phase degreasing.

Despite its environmental advantages over vapor phase degreasing withrespect to ozone depletion, if not managed properly, aqueous phasedegreasing can create environmental problems of its own. The problem ofwaste water and water pollution is of tremendous concern. As a result,it would be highly desirable for the metal working industry to utilizean aqueous phase degreasing procedure in which the aqueous degreasingsolution could be recycled and reused as feeder solution for a metalcutting machine coolant, which is itself recyclable and reusable.Tremendous benefits could be reaped by minimizing worker exposure toharmful substances, as well as reducing or eliminating hazardous wastestreams.

SUMMARY OF THE PRESENT INVENTION

A method and apparatus for cooling and washing metal parts whichincludes washing the metal parts in a degreasing solution, mixing theused degreasing solution with a coolant solution and using the mixtureas a coolant in a metal forming operation is disclosed. In this way thewash solution is recycled and reused. The apparatus includes a washstation, rinse station and drying station through which the parts aremoved sequentially. The apparatus further includes a counterflow offluid beginning in the rinse tank and moving downstream through the washtank at a predetermined rate. The used wash solution is collected forrecycling. Also disclosed is a skimming operation and a method ofseparating degreasing solution from the coolant mixture for recycling inthe degreasing system. The method includes using ultrafiltration andprecipitation to separate the components.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention will be seen uponreference to the following detailed description, when read inconjunction with the accompanying drawings, wherein like referencenumerals refer to like parts throughout the several views, and in which:

FIG. 1 is a block diagram setting forth the steps in the process ofrecycling and reusing an aqueous degreasing solution into a coolantsolution;

FIG. 2 is a block diagram in which an ultrafiltration step has beenadded to the recycling process;

FIG. 3 is a perspective view of the degreasing system in accordance withthe invention;

FIG. 3A is a schematic view of the degreasing system according to theinvention;

FIG. 4 is a cross-sectional view of a skimmer in accordance with theinvention;

FIG. 5 is a cross-sectional view of a wash bath in accordance with theinvention;

FIG. 6 is a partial perspective view of a portion of a carrier and bathin accordance with the invention; and

FIG. 7 is a cross-sectional view of a carrier showing baskets inaccordance with the invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE PRESENT INVENTION

With reference first to FIG. 1, a block diagram of a process in whichused degreasing solution is recycled and reused in a coolant solutionfor metal cutting machines, which is itself recycled and reused, isthereshown. Raw metal 10 is sent to a cutting machine 12 to be cut intoformed metal parts 14. The formed part 14 exits the cutting machine 12on a conveyor belt (not shown). Metal shavings 16 accumulated during thecutting process exit off a second conveyor belt (not shown). Both theformed metal parts 14 and the metal shavings 16 are covered inlubricating oils 18 and coolant solution 20 as a part of the metalcutting process.

The coolant solution 20 that is utilized in the cutting machines 12contains approximately 2-7% by volume water miscible cutting andgrinding fluid concentrate 28 (Masterline Brass Cut available fromMaster Chemical Corporation in Perrysburg, Ohio), approximately 1-2%water miscible washing compound concentrate 30 (Masterline Brass Clearavailable from Master Chemical Corporation in Perrysburg, Ohio), and thebalance purified water. The water miscible washing compound concentrate30 causes excessive foaming within the cutting machine 12 at aconcentration above 2%. All of the water miscible washing compoundconcentrate 30 that is used in the coolant solution 20 is taken from theaqueous phase degreasing system 32.

The water miscible washing compound concentrate 30 contains 40-50% byweight amine carboxylate, 10-20% nonionic surfactant, 1-10% pine oil,less than 1% glycol, less than 1% substituted indole, and the balancewater. The amine carboxylate is formed by dissolving a carboxylic acidin an excess of amine. The substituted indole is preferably asubstituted triazole.

The water miscible cutting and grinding fluid concentrate 28 contains60-70% by weight petroleum oil, 20-30% petroleum sulfonate, 1-10%nonionic surfactant, 1-10% aromatic alcohol, 1-10% propylene glycolether, less than 1% propylene glycol, less than 1% substituted indole,less than 1% carboxylic acid, less than 1% blue-green dye, less than 1%silicone defoamer, and the balance water. The aromatic alcohol ispreferably a halogen substituted aromatic alcohol. The substitutedindole is preferably a substituted triazole.

In the present embodiment, the water miscible washing compoundconcentrate 30 has the following composition (% w/w): 33.000 water;0.300 tolytriazole (35% solution); 2.200 oleic acid; 0.0200 siloxaneantifoam; 50.980 triethanol amine (99.9%); 12.500 nonylphenol ethoxylate(5 mole wt); 1.000 α-terpineol.

The water miscible cutting and grinding fluid concentrate has thefollowing composition (% w/w): 65.725 naphthenic oil (100 SUS); 18.000sodium petroleum sulfonate w/ pine oil and glycol; 5.00 water; 4.20nonylphenol ethoxylate (10 mole wt); 2.50 ethylene oxide/propylene oxidecopolymer (mw˜332); 2.00 p-chloro-m-cresol; 1.00 tripropyleneglycolmonoethylether; 0.600 tolytriazole (35% soln); 0.300 oleic acid; 0.300phosphate ester (RP Ant LB 400); 0.275 potassium hydroxide (50% soln);0.100 siloxane antifoam.

In the course of running the metal cutting machine 12, the coolantsolution 20 becomes mixed with tramp oils, dirt, and metal shavings 16.This dirty coolant 22 is collected from the cutting machines 12 into aholding tank 24. At the same time, the metal shavings 16 coming off theconveyor are collected and sent through a squeezer 26 to squeeze off thedirty coolant 22. This dirty coolant 22 from the metal shavings 16 isalso sent to the holding tank 24.

The metal parts 14 covered with oils and coolant solution 20 are takenfrom the cutting machines 12 and sent through an aqueous phasedegreasing system 32 to be discussed more fully below. The parts 14 areimmersed in a series of wash baths or tanks 34 at approximately 160° F.containing approximately 2-6% of the water miscible washing compoundconcentrate 30 and the balance chemically purified water 31, forming anaqueous degreasing or wash solution 35. The parts are then immersed in aseries of purified water rinse baths 36, sent through a dryer 38, andthen sent off for further use in manufacturing operations or as finishedparts 40. Oils coming off the parts 14 during washing are skimmed offthe tops of the wash baths 34, and the used aqueous degreasing solution42 is collected off of a wash bath 34 and sent to the dirty coolantholding tank 24 where it becomes a feeder solution for the coolantsolution 20. The entire aqueous phase degreasing system 32 is controlledso that the used aqueous degreasing solution 42 can be collected from awash bath 34 at a rate sufficient to permit total use of the usedaqueous degreasing solution 42 in the coolant solution 20. In apreferred embodiment, the used aqueous degreasing solution 42 iscollected from a single wash bath 32 at a rate of 1/2 gallon/minute,with 100% of the used aqueous degreasing solution 42 being recycled andreused as a feeder solution for the dirty coolant 22. None of the usedaqueous degreasing solution 42 is sent out as waste.

The dirty coolant 22 which has been gathered into a holding tank 24 fromthe metal cutting machines 12, the squeezed metal shavings 16, and thewash baths 34 of the aqueous phase degreasing system 32 is then sentthrough a high speed disc bowl centrifuge 44 where the contaminatingtramp oils and other contaminants are "spun out." This cleaned andrecycled coolant solution 20 is then sent to a clean coolant reservoir48 (FIG. 2) where the proper concentrations of water and water misciblewashing compound concentrate 30 are maintained prior to introduction ofthe clean coolant solution 20 back into the metal cutting machines 12.

Because all of the used aqueous degreasing solution 42 from the aqueousphase degreasing system 32 is being reused as feeder solution for thedirty coolant 22, problems can arise with the cutting machines 12 if thelevel of water miscible washing compound concentrate 30 from the usedaqueous degreasing solution 42 becomes too high in the coolant solution20 introduced back into the cutting machines 12. One problem thatresults is foaming within the metal cutting machine 12, and the otherproblem that results is elevated concentrations of the metals beingmachined in the coolant solution 20. The metal contaminants build up inthe used aqueous degreasing solution 42 as a natural outcome of cuttingand washing the metal parts 14.

The used aqueous degreasing solution 42 (along with the metalcontaminants) is then added into the holding tank 24 along with theother dirty coolant 22 that has been collected. Centrifugation 44 onlyremoves dirt and tramp oil from the dirty coolant 22. One way to controlthe concentrations of metal contaminants and water miscible washingcompound concentrate 30 in the coolant solution 20 that is sent back tothe cutting machines 12 is through ultrafiltration 50.

With reference now to FIG. 2, an ultrafiltration step 50 can be added tothe overall process of recycling and reusing an aqueous degreasingsolution 35 as a feeder solution for a dirty coolant solution 22 whichis also recycled and reused. After the dirty coolant is centrifuged 44,but before it is sent back into the cutting machines 12 a portion of theclean coolant 20 is sent through an ultrafiltration unit in which theretentate 52 contains primarily water miscible cutting and grindingfluid concentrate 28, and the permeate 54 contains primarily water,metal contaminants, and water miscible washing compound concentrate 30.The metal contaminants come through the ultrafiltration unit 50 indirect proportion to the water miscible washing compound concentrate 30.Removal of an amount of coolant 20 necessary to prevent buildup of metalcontaminants and washing compound concentrate 30, and to maintain anequilibrium in the coolant 20 for passage through the ultrafiltrationunit 50 is effective in keeping the concentrations of heavy metals andwater miscible washing compound concentrate 30 under control beforesending the clean coolant 20 back into the cutting machines 12. In thepresent embodiment as little as 1% of the system volume of coolant 20 isremoved per day for passage through the ultrafiltration unit 50.

The permeate 54 containing water, water miscible washing compoundconcentrate 30, and metal contaminants can then be further purified toremove the metal contaminants. Once separated by ultrafiltration 50 boththe retentate 52 and the permeate 54 (absent the metal contaminants) canbe reused and recycled back into the cutting machines 12 or wash baths34 respectively, or sent to waste treatment. The additional step ofultrafiltration 50 allows for the levels of water miscible washingcompound concentrate 30 and metal contaminants in the clean coolantsolution 20 to be better controlled before the clean coolant 20 goesback into the cutting machines 12, without the necessity of decantingthe coolant solution 20 several times a year to keep the coolantsolution 20 properly balanced. Alternatively, in the present embodiment,the dirty coolant 22 can be removed from the dirty coolant holding tank24 and sent through the ultrafiltration unit 50.

As best shown in FIGS. 3 and 3A, the degreasing system 32 includes anautomated apparatus for removing coolant solution from the metal parts14. The metal parts 14 are moved in a parts carrier 102 by a pair ofhoists 140,141 sequentially through a series of stations including aloading/unloading station 104, a wash station 106, a rinse station 108,and then to a drying station 110. The wash station 106 includes a seriesof three wash baths 34 and skimmers 136 which skim oil from a washsolution. The rinse station 108 includes four rinse baths 36.

The degreasing system 32 utilizes a flow of liquid which begins withchemically purified water 31 from a water supply 33 which is introducedat the rinse station 108 and flows downstream through the wash station106 where the washing compound concentrate 30 is added to form a washsolution 35. Thus, the metal parts 14 are moved upstream throughincreasingly clean liquid during the degreasing operation.

The loading station 104 consists of a conveyor 114 which is driven by anelectric motor (not shown). Operation of the motor is controlled by acentral processing unit 116 to move the parts carrier 102 between aloading position (Shown in FIG. 3) and a staging position. The parts 14are delivered in metal baskets 118 (shown in FIG. 7) to the loadingstation 104 from the cutting machine 12. The metal baskets 118 haveopenings in all sides to permit the wash solution and rinse water topass through and drain from the baskets 118.

As shown in FIGS. 3 and 7, the carrier 102 includes a drum 120 which ismounted for axial rotation in a frame 122. The drum 120 is formed of ametal lattice which permits liquid to pass through to the baskets 118and parts 14. The drum 120 has pairs of jaws 121 which move apart topermit access to an interior compartment formed to hold stacks of themetal baskets 118 containing the parts 14. The jaws 121 are movedtogether to lock the baskets 118 in position within the carrier 102. Theframe 122 includes an elongated bridge 124 which extends between a pairof vertical end panels 126. The panels 126 have flat bottom surfaces andare dimensioned to keep the bridge above the surface of the liquid inthe wash station 106 and rinse station 108. The drum 120 is mountedbetween the end panels 126 beneath the bridge 124. A D/C motor 130 ismounted to a top surface of the bridge 124. The motor 130 is connectedin a suitable manner such as a belt or drive rods and gear mechanisms toselectively rotate the drum 120.

As best shown in FIG. 6, three metal L-shaped arms 132 extend outwardlyfrom each of the end panels 126 to provide electrical current for theD/C motor. The arms 132 are spring biased to permit movement along avertical axis and are positioned so as to contact electrical contacts134 positioned adjacent to each bath 34,36. As will be described below,the motor 130 may be selectively energized to rotate the drum 120 whenthe carrier 102 is immersed in the baths 34,36 or suspended by either ofthe two hoists 140,141. A pair of lifting pegs 142 are positioned oneach end panel 126, one on either side of the arms 132 for engagementwith lift hooks of the hoists 140,141. The baskets 118 are loaded intothe parts carrier 102. After the parts carrier 102 is loaded, theconveyor 114 moves the carrier 102 to a staging position adjacent thewashing station 106.

As best shown in FIGS. 3 and 5, the wash station 106 includes threeidentical baths 34. Each of the baths 34 is rectangular, having a pairof sides 146, a pair of ends 148, 150 and a bottom 152. The bottom 152of each bath 34 has a rectangular channel 154 formed along one side forhousing an auger 156. The auger 156 is turned by an electric motor (notshown). The bottom 152 has a central portion 158 which slopes downwardlytowards the channel 154 to deliver any metal flakes or debris from theparts 14 into the channel 154. The auger 156 carries the debris throughthe channel 154 to a drain 160 having a trap 161 for capturing thedebris. The trap 161 is a removable basket for disposing of the debris.

As shown in FIGS. 3, 5 and 6, a steam pipe 162 delivers steam to thesides 146. A conduit 164 delivers the steam from a boiler 166 to aheating coil 167 positioned beneath each tank 34,36 to heat liquid inthe tanks 34,36. The water is heated to approximately 160° F. Ultrasonicwave generators 168 are mounted between the sides 146 of the baths toproduce waves which move the liquid between the parts 14 in the baskets118 to permit the fluid in the tanks 34,36 to pass fully around theparts 14. This facilitates cleaning of the parts 14 and removal ofresidual debris. The ultrasonic generators 168 may be of anyconventional type.

As shown in FIGS. 3 and 5, a horizontally aligned manifold 169 having anumber of jets 170 is mounted near the top of each tank 34,36. Theliquid is sprayed through the jets 170 into the tank 34,36. The washingsolution 35 is delivered to the manifold 169 by a pump 172 and inflowconduit 174 from an associated skimmer 136. The washing solution ispermitted to flow over a weir 173 into a collector 175 located at oneend 148 of the tank 34,36 from which it is gravity fed through anoutflow conduit 176 back to the skimmer 136.

As shown in FIGS. 3 and 4, each of the skimmers 136 is a rectangulartank having a main chamber 178, an intermediate chamber 180 and acollector 182. The main chamber 178 is defined by a pair of side walls184, an outer end wall 186 and an interior wall 188 which extendstowards an opening 190 at the bottom of the tank. The out flow conduit176 delivers fluid from the baths through a series of large apertures192. The fluid is delivered by gravity into the main chamber 178 and isallowed to flow into the tank through the apertures 192 below a baffle193 to prevent turbulence so that any tramp oil in the liquid will riseto the surface of the liquid of the main chamber 178 where it will floatto be collected by a skimming device. The skimming device may be of anysuitable type for removing oil. It may be performed by hand or amechanical device as known in the art and may be used to siphon oil fromthe top of the main chamber 178 and delivered by a conduit 196 to areservoir. The liquid is circulated through a filter 197 to removeparticulate matter from the liquid.

The liquid flows from the main chamber 178 through the opening 190 intothe intermediate chamber 180 formed between the interior wall 188 and aprimary weir 198 which is lower than the interior wall 188. The liquid(shown by arrow A) is permitted to cascade over the weir 198 into thecollector 182 from which it is delivered to the inflow conduit 174 andpump 172 for delivery to an associated bath 34,36. A secondary weir 200is formed in each side wall 184 of the collector 182 between collectorsof adjacent skimmers 136 to permit a portion of the liquid to passdownstream to the collector 182 of the adjacent skimmer (shown by arrowB). Thus, there is a downstream counterflow from 136d to 136c to 136band 136a as shown in FIG. 3A when the rinse water flows to skimmer 136cit is mixed with the aqueous degreasing solution 35, from wash bath 34c.The wash solution is, thus composed of the rinse water and approximately2 to 7% and preferably 3 to 4% of the washing compound concentrate 30.The concentration of washing compound concentrate 30 is monitored andcontrolled in each wash bath 34 on a daily basis. It has been found tobe advantageous to maintain the concentration of the first two baths34a,34c that the parts 14 enter at 4%, and the concentration of thethird bath 34c at 3%.

As shown in FIG. 3A, the wash solution 35 is delivered from the washbath 34c to a skimmer 136c and then to the skimmer 34b. Where it isrecirculated to wash bath 134b, the wash solution continues downstreamto skimmer 136a and to the first wash bath 34a. The used aqueousdispensing solution 42 is delivered through a conduit 202 from theskimmer 136a to the dirty coolant tank 24 for use as feedstock in thecoolant solution 20.

The rinse station 108 includes four baths 36, one bath 36 is separatedfrom the other rinse baths by a holding table 204. Each of the rinsebaths 36 is generally rectangular shaped, having the same dimensions asthe wash baths 34. However, the rinse tanks 36 do not include a channel154 and auger 156 at the bottom as do the wash tanks 34. Steam isdelivered from the conduit 164 to the bottom of the tanks 36 in order toheat the rinse water 31. A suitable temperature is approximately 155° F.A weir 208 is formed at one end to permit the rinse water 31 to flowfrom the bath 36 into a collector 210 from which it is delivered by aconduit 212 and pump 211 to the manifold 169 having jets 170 to thedownstream tank. The rinse water 31 is introduced from the water supply33 through a flow regulator (not shown) into the fourth rinse bath 36 ata rate of between 0.1 and 1.0 gallon per minute. The rate in thepreferred embodiment is 1.0 gallon per minute. However, the rate of flowof liquid through the system decreases to approximately 0.5 gpm becauseof evaporation from the baths. Thus, the flow rate of liquid is lower ineach downstream bath 34,36.

As described above, the rinse water 31 cascades downstream through eachof the four rinse baths 36, weirs 208 and collector 210 to the mostupstream skimmer 36 where it is then introduced into the third or mostupstream wash bath where it is mixed with the washing compoundconcentrate 30.

As shown in FIGS. 3, 3A, and 5, the drying station 110 incudes threerectangular drying chambers 213 having the same dimensions as the washand rinse baths 34,36. The drying chamber 213 are heated by a heatingcoil 167 connected to the conduit 164 to receive steam from the boiler166. The carrier 102 may be thus placed in a chamber 213 and receiveheat from the coil 167 to dry the parts 14 inside the drum 120.

In the event that the degreasing system 32 needs servicing, the rinsewater 31 and washing solution 32 may be pumped into two tanks 214, 215for storage during service.

The two hoists 140, 141 each run on a pair of overhead rails 216. Theoperation of the hoists 140, 141 is controlled by the CPU 116 which bothcontrols the movement of carriages 218 along the rails 216 and operateschains 222 to raise and lower a lifting plate 220. As shown in FIGS. 3and 6, each of the lift plates 220 has a pair of V-shaped receptacles224 which extend inwardly. The receptacles 224 are spaced apart andpositioned to receive the lifting pegs 142 of the carrier 102.Electrical contacts are provided on the carriage 218 to connect with thearms 132 on the carrier 102 to power the electric motor 130 to rotatethe drum 120. The hoists 140,141 are operable to raise and lower thecarrier 102 to and from the baths 34,36 and to rotate the drum 20 whenthe 120 are in a raised position. The first of the hoists 140 is a washhoist movable between the staging area of the loading station 104 andthe holding station 204. The rinse hoist 141 moves between the firstrinse bath and the drying station 110.

OPERATION

Parts 14 are delivered to a carrier 102 at the loading station 104 wherethe baskets 118 are loaded into the drum 120. After being loaded, thejaws 121 of the drum 120 are closed and the carrier 102 is moved alongthe conveyor 114 to the staging area. The carrier 102 is then lifted bythe wash hoist 140 and delivered to the first wash bath 34a. The washbath 34a (FIG. 3A) contains a washing solution 35 which is heated to atemperature of approximately 160°. The parts 14 are subjected toultrasonic agitation and may be rotated within the bath 34 by turningthe drum 120. After approximately one minute in the first bath 34a, thecarrier 102 is lifted by the wash hoist 140 and moved to the second andthird wash baths 34b and 34c. The carrier 102 remains in each bath 34for approximately one minute before it is moved onto the subsequent bath34. After passing through the third wash bath, the carrier is lifted bythe wash hoist 140 and deposited at the holding station 204.

The rinse hoist 141 then lifts the carrier 102 into the first of therinse baths 36. The carrier 102 is then subsequently positioned in thesecond, third, and fourth rinse baths 36. The carrier 102 is held ineach bath 36 for approximately 15 to 20 seconds. After completing thefour rinse baths 36, the rinse hoist 141 moves the carrier 102 to one ofthe drying chambers 213 while the hoists 140, 141 move other carriers102 through the rinse and wash baths 34,36. The carrier 102 is permittedto remain in the drying chamber 213 nearly three full wash and rinsecycles, or approximately 15 minutes. After the carrier 102 has completeda drying period, it is removed from the drying chamber 213 by the rinsehoist 141 and is returned to the holding station 204. The wash hoist 140then moves the carrier 102 to the loading area of the loading station104 where the baskets 118 are unloaded. The timing of the movement ofthe carriers 102 may be programmed such that the carriers 102 are beingcontinuously and progressively moved through the various baths 34,36 andreturned to the loading station 104. The movement of the carriersthrough the degreasing system 32 is controlled by the CPU 116.

When fully lifted, the drum 120 of the carrier 102 may be rotated todrain the wash solution 35 or rinse water 31 from the drum 120 beforemoving on to the next bath 34,36. However, if the parts 14 are requiredto have a smooth finish, then the drum 120 is not rotated. Additionally,the rotation of the drum 120 can be controlled to provide either acontinuous rotation or a staggered rotation where the drum 120 moves 90°and is held for a period of time before rotating another 90°. One of thearms 132 provides electrical contact for continuous rotation, a secondfor staggered and a third is a ground.

The present invention, therefore, provides for a coolant and aqueousdegreasing reclamation process for the metal finishing industry in whichthe used aqueous degreasing solution is recycled and reused into thecoolant solution which is itself recycled and reused. As a result, theuse of ozone depleting or carcinogenic substances is avoided and theneed for sending used solutions into waste water is greatly diminished.Having described my invention, many modifications thereto will becomeapparent to those skilled in the art to which it pertains withoutdeviation from the spirit of the invention as defined by the scope ofthe appended claims.

We claim:
 1. A method for recycling a coolant solution for use incooling raw metal being cut in a metal cutting machine, said methodincluding the steps of:cutting raw metal in a metal cutting machinewhile directing a stream of a coolant solution thereonto, said coolantsolution comprising a supply of a water miscible, cutting fluidconcentrate dispersed in water, whereby a part is produced from saidmetal and a volume of used coolant solution is generated; conveying saidpart to a degreasing station which operates to wash said part in adegreasing solution which comprises a supply of a water miscible washingcompound concentrate dispersed in water, whereby a cleaned part isproduced and a volume of used degreasing solution is generated; cleaningsaid volume of used coolant solution so as to remove insoluble oils andcontaminants therefrom; cleaning said volume of used degreasing solutionso as to remove insoluble oils and contaminants therefrom; and mixingsaid used coolant solution, said used degreasing solution and sufficientcutting fluid concentrate so as to regenerate the coolant solutionhaving said supply of said cutting fluid concentrate therein.
 2. Amethod as in claim 1, wherein said used coolant solution and said useddegreasing solution are mixed together prior to being cleaned, andwherein the steps of cleaning said used coolant solution and said useddegreasing solution are carried out at the same time, on said mixedsolutions.
 3. A method as in claim 2, wherein said cutting fluidconcentrate is added to said mixed solutions after they have beencleaned.
 4. A method as in claim 1, wherein the step of cleaning saidvolume of used coolant solution and the step of cleaning said volume ofused degreasing solution are carried out by use of a centrifuge.
 5. Amethod as in claim 1, wherein said coolant solution comprises, byweight, 2-7% of said cutting fluid concentrate.
 6. A method as in claim5, wherein said coolant solution further includes, by weight, 1-2% ofsaid washing compound concentrate.
 7. A method as in claim 1, whereinsaid degreasing solution includes, by weight, 2-6% of said washingcompound concentrate.
 8. A method as in claim 1, wherein the step ofconveying said part to a degreasing station comprises conveying saidpart to a station which further operates to rinse the part in water,after said part has been washed in said degreasing solution, and whereinat least a portion of the water in which the part has been rinsed issubsequently mixed into the degreasing solution.
 9. A method as in claim1, wherein the step of cleaning said used degreasing solution includesthe step of filtering at least a portion of said used degreasingsolution through an ultra filter so as to remove at least a portion ofthe washing compound concentrate, and a portion of metal contaminantsfrom said used degreasing solution.
 10. A method as in claim 1, whereinall of said used degreasing solution is mixed with said used coolantsolution.